Re: Dynamic polymorphism vs. Static polymorphism

From:
"mlimber" <mlimber@gmail.com>
Newsgroups:
comp.lang.c++
Date:
30 May 2006 10:31:23 -0700
Message-ID:
<1149010283.883957.303810@i39g2000cwa.googlegroups.com>
Ulrich Hobelmann wrote:

Krivenok Dmitry wrote:

Hello all!

Perhaps the most important feature of dynamic polymorphism is
ability to handle heterogeneous collections of objects.
("C++ Templates: The Complete Guide" by David Vandevoorde
and Nicolai M. Josuttis. Chapter 14.)

How to implement analogue of this technique via static polymorphism?
Perhaps there is special design pattern for this purpose...


There are many concept that are called polymorphism or genericity:
http://en.wikipedia.org/wiki/Polymorphism_%28computer_science%29

Which ones do you mean (especially with "static polymorphism") exactly?


He means C++ templates, but the question is too broad to be answered
completely here. One could implement static polymorphism like this:

 struct A
 {
   int Read(); // Does something
 };

 struct B
 {
   int Read(); // Does something else
 };

 template <class T>
 class Reader
 {
   T& t_;
 public:
   Reader( T& t ) : t_( t ) {}

   int DoSomething()
   {
     return t.Read();
   }
 };

This template is basically the same as using an abstract base class
with a virtual Read(), but it achieves the same effect without
virtuality, which can sometimes be useful.

Cheers! --M

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